PB2086: CHRONIC LYMPHOPROLIFERATIVE DISORDER OF NK CELLS WITH LIVER INFILTRATION
Authors: V. Otasevic, D. Antic, V. Vukovic, V. Djurasinovic, K. Tomic, B. Mihaljevic
Journal: HemaSphere (2022)

Background: Chronic lymphoproliferative disorder of natural killer (NK) cells (CLPD-NK) represents exceptionally rare and heterogeneous indolent disorder, which has various clinical manifestations. Infrequently CLPD-NK can present with several non-indolent features, potentially mimicking more aggressive clinical entities (such as aggressive NK cell leukemia). Aims: We report the case of CLPD-NK with liver infiltration, extreme splenomegaly and direct Coombs negative hemolytic anemia. Methods: The patient was thoroughly examined both in ambulatory and hospital conditions. The pleiad of diagnostic tools and procedures was used, ranging from variety of laboratory examination of blood samples, radiological diagnostic procedures (for instance, computerized tomography) and invasive diagnostics (bone marrow biopsy, lymph node biopsy and blind percutaneous liver biopsy). Results: A 42 years-old male patient presented with B symptoms that lasted for 3 months. After exclusion of infective and immunologic etiology of the condition, the patient was referred to hematologist. Complete blood count (CBC) demonstrated normocytic anemia (Hb 79 g/L, MCV 81 fL), leucocytosis (11.4 x109/L) with lymphocytosis (72%) and NK cells (14%) in peripheral blood smear, accompanied with presence of spherocytes and reticulocytosis. Negative direct Coombs test was observed together with indicators of hemolytic anemia (indirect hyperbilirubinemia, unmeasurable haptoglobin level and elevated level of lactate dehydrogenase). By both physical examination and ultrasound, hepatomegaly (CC 17cm) and extreme splenomegaly (CC diameter 25cm) was revealed, together with axillary lymphadenopathy (up to 26mm). By bone marrow examination lymphocytic infiltration was excluded. Immunophenotyping of peripheral blood showed that 91% of circulating lymphocytes (9.88x109/L) were NK-lymphocytes with distinctive immunophenotype profile (CD2, CD7, CD16)+/(CD3, CD56)- (Figure 1). Additionally, axillar lymph node biopsy was performed and pathohistological analysis showed sinus histiocytosis. Because of extreme splenomegaly and non-homogenous structured hepatomegaly, the patient was examined by gastroenterologist which indicated and afterwards performed blind liver biopsy. The pathohistological analysis of the liver biopsy indicated that the most favourable diagnosis is liver infiltration of CLPD-NK, with possible differential diagnosis of hepatosplenic T-cell lymphoma and EBV negative aggressive NK cell leukemia. Considering this finding, the fact that patient was corticosteroid resistant and that the patient’s condition and CBC parameters were significantly deteriorating, he was administered with one cycle of CHOP chemotherapy regimen. The therapy was complicated by febrile neutropenia which demanded hospital treatment, with prolong neutropenia grade II-III and the persistence of all previously mentioned symptoms and signs of disease activity. Following this, the peroral cyclophosphamide and prednisolone combination therapy was initiated and resulted in complete remission inside of 4 months from the treatment initiation. Image:Summary/Conclusion: CLPD-NK is highly uncommon and indolent disorder, with wide variety of clinical presentation. The backbone of the diagnostic approach and consequent adequate treatment is the differentiation the condition from more aggressive entities.